This invention relates to improvements in heavy-duty detergent compositions and to the problems which such heavy-duty detergents cause when they are sent into rivers, lakes and seas having living fishes and similar aquatic and marine life.
The prior art relative to detergent compositions for various uses probably finds its origin in prehistoric eras and, to say the least, is extensive. The use of true soaps and, in contrast, synthetic surfactants, such as anionic, nonionic, cationic and mixed types, alone, and with builders, is well documented, with indicated efficacies for a multitude of applications. The prior art also teaches the use of various amphoteric type surfactants in detergent applications (See, for example, U.S. Pat. Nos. 3,719,613, 3,452,065, 3,654,166, 3,280,179). The widespread use of amphoteric surfactants was probably precluded for economic reasons. The largest commercial and household usage of surfactants is comprised of true soaps, alkyl aryl sulfonates, alkyl sulfates, and nonionics of the ethyl-oxylated nonyl and octyl phenols and alcohol types. In recent years considerations of biodegradability have caused changes to linear alkyl aryl sulfonates, straight chain alcohols, etc. Thus, the situation exists that very large tonnages of the above-described detergent types are being released to sewage effluents and surface waters.
Although control of water-pollution, both Federal and State, dates back many years, it was not until the Federal Water Pollution Control Act Amendments of 1961 that the significance of the program was elevated. Finally, the Federal Water Pollution Control Act Amendments of 1972 established firm guidelines as to what constituted water pollution. One requirement arising from these new regulations reads that no discharge into sanitary sewer systems of industrial waste having a 96-hour median tolerance limit (TLm) of less than 50% would be allowed. To determine the toxicity of various substances to marine and aquatic life other than microorganisms, standard methods of bioassay are used. (See, for example, Standard Methods for the Examination of Water and Waste Water, 13th Edition, prepared and published jointly by American Public Health Association, American Water Works Association, Water Pollution Control Federation, Publication Office; American Public Health Association, 1740 Broadway, New York, N. Y. 10019, Section 231, and Water Quality Criteria, Publication 3-A, California State Water Resources Control Board). The terms "TL 50" and "TLm 50", indicate the tolerance limits at existing or stated concentration of indicated pollutants. Fish survival tests indicate percent of fish surviving in a given solution or effluent in a given period of time. In all cases, our tests were run for a 96-hour period. For our purpose, the terms TL, TLm, and percent survival, are used interchangeable and when 50 or greater, indicate substantial or acceptable nontoxicity to marine or aquatic life other than microorganisms, in accordance with the standard assays. In this specification and claims it will be understood that marine or aquatic life is intended to mean "other than microorganisms." It is known that none of the detergent compositions utilizing the known true soaps, anionic, nonionic or cationic types would pass this Fish Bio-Assay Test at usual use concentrations.
As stated above the prior art teaches widespread detergent applications utilizing true soaps and synthetic surfactants of anionic, nonionic and cationic types. Again, for the purpose of brevity, these will be referred to as SANC, such an abbreviation indicating compositions of the aforementioned types, alone, mixed, or admixed with builders and suitable adjuncts.
In considering water-pollution aspects it is pointed out that not only the TLm but other restrictions are also placed on the composition of sewage effluents. In part, these would include limits in content of grease, suspended matter, chemical oxygen demand, pH range, temperature, metal content, sulfides, cyanides, phenols, chlorinated hydrocarbons, etc. Thus, it is the intent by statute to limit by prescribed maximum figure, or by a range, the inclusion of these varied substances and conditions in industrial wastes. Where violation occurs it is the responsibility of the polluter to take measures to bring the effluent within the statute requirements. It is further pointed out that many, but not all of the SANC type detergents would not contribute to violations of the latter described type, and that their known efficacy as detergents could still be utilized. However, even if none of these latter violations existed in effluents containing SANC type materials, the effluent would still be in violation because the presence of SANC types would be toxic as determined by the TLm. The removal of SANC types to safe tolerance limits (generally reported as 5-25 parts per million) from the effluent would be a costly process, and becomes unnecessary through the use of the improved detergent compositions of this invention which provides the basis for adequate detergency while still passing the TLm.
Pursuant to this invention the inventors have found that the novel detergent compositions containing the amphoteric surfactants described provide at least equivalent detersive effects as the SANC types, and that these novel compositions provide improvement in overall detersive effects to be described in greater detail later, and that, principally, these novel detergent compositions, after providing these improved detersive effects will not make the dumped waters (sewage effluent) toxic as determined by the TLm.